Varying electrical acupuncture stimulation intensity: effects on dental pain-evoked potentials.

Electrical acupunctural stimulation (EAS) has repeatedly been shown in the laboratory to diminish human dental pain perception. This study compared the effects of low, medium, and high EAS levels on event-related potentials elicited by painful dental stimulation and on subjective pain report. Acupuncture was performed bilaterally at LI-4 on the hands, and each subject received all EAS levels, counterbalanced for order. Only the highest level of EAS was effective, and it reduced the pain report in addition to the amplitudes of the positive event-related potential deflections from base line at 100 and 250 msec. No dose-response effect was observed for EAS levels. The outcome suggests that the analgesic effect occurs abruptly when stimulation reaches a strong level and a subnoxious pounding sensation is elicited.